Rotary field-magnet with parallel grooves for the windings.



, F. LIUNGSTRUM. ROTARY FIELD MAGNET WITH PARALLEL GROOVES FOR THE WINDINGS.

APPLICATION FILED APR. I6 19].).

Patented Oct. 29, I918.,

w /M Y WWW/LL UNITED STATES PATENT oEEIoE.

EEEDEIK LJUNGsTEoM, or FINSPONG, SWEDEN, ASSIGNOR To AKTIEBOLAGET LJUNGsTEiiMs JINGTURBIN, 0E FINSPONG, SWEDEN.

- ROTARY FIELD-MAGNET WITH PARALLEL GROOVEQ FOR THE WINDINGS.

Application filed April 16, 1915.

' To all whom it may concern:

Be it known that I, FREDRIK LJUNG- s'rnoir, engineer, a subject of the King of Sweden, residing at Finspong, Sweden, have invented certain new and useful Improvements in Rotary Field-Magnets with Parallel Grooves for the WVindings, of which the following is a specification.

In rotary field-magnets with parallel grooves for the field-winding intended for fast goingturbogenerators or machines of .a similar rapidity rotators of the so called Lamme-type are now chiefly used. The invention relates to certain unprove- In the Lamme- "type a central core, forming the rotary field is used which core is rovided with P parallel grooves, separated from each other by partitions forming parts of the core or attached thereto, which grooves receive the field-winding. The latter is prevented from being thrown out by the centrlfugal force "by. means of metal wedges. The central core is at both ends attached to the end plates ofthe two shaft sections by fastening screws or bolts applied to the pole-shoes at points almost as far from the axis of the rotator as is the periphery of the latter.

A metal space plate is often placed between tions are unsatisfactory because they yield to the radial expansion of said space plate and other parts under such centrifugal tens1on..

Though experience has proved that such rotators in spite of this defect could be used, they have lacked strength, durability and accuracy and the exact balancing of such rotators has been specially difficult.

- According to this invention these difficulties are overcome by placing the screw fastenings at so short a radial distance from the axis that the centrifugal strain is very slight, which is made possible by applying the fastening screws to a longitudinally projecting part of the rotator body, sa d part being cylindrical and concentric with the Specification of Letters Patent.

PatentedOct. 29, 1918.

Serial No. 21,884.

half of said view being taken with the end wedges, space block and binding bolts removed and the lower half of said view being taken with the space block and binding bolts in position; and

Fig. 3 is on a larger scale than Fig. 2 and the right half of Fig. 3 corresponds to the right half of the upper half of Fig. 2, the end plate, spacing block and bolts being removed, while the left half of Fig. 3 similarly corresponds to the left half of the upper half of Fig. 2, the same parts and also the terminal transverse wedges being removed, and the longitudinal wedges being shown in vertical section on the line A-B of Fig. 1.

The longitudinal grooves e of the body leave the usual partitions or ribs or between them. Longitudinal wedges c are fitted into the same and transverse terminal wedges a, practically in continuation of the wedges 0, are fitted into the ends of said grooves at the ends of the said rotator body. Each partition (6 has an extension at each end, and these extensions with corresponding parts of the terminal wedges, are so shaped and arranged, as to form collectively a cylindrical extension I) ateach end of the body of the magnet, such extension Z) having a less diameter than the body aforesaid and corresponding in form size and position to its central part only.

In this cylindrical extension Z) threaded holes are made, into which the fastening screws d are. screwed. Between-the wedges and the central part of the body, in grooves e, the windings are provided. In this way a strong fastening is effected between the rotator body and the end plates of the shaft sections with a diameter small enough to prevent the centrifugal strain from becoming too high and which also permits the applying of the fastening screws in a continuous circle, contrary to the construction used by Lamme, in which the bolts are placed only in the rotator-body. In calculating the solidity of rotators of the con struction in question the component of'the centrifugal force has proved'to' be of such large dimensions that .a very. great bending strain arises in the partitions. Accordingly it is most important to get wedges between the said partitions of such a form that they as much as possible prevent -too great a strain. The usual space plates or blocks f of disk form are interposed between the extensions b of the rotor and the end plates other face it has projections fitting into thev correspondingly recessed face of the contiguous extension I But these details are apart from the invention clai'medand it is unnecessary to exactly adhere to them. Each of these space blocks is also bored to permit the passage of the circular series of binding bolts d. I

Part of the invention refers to the con-- struction of the said wedges which on both sidesare provided witha number 'of longitudinal serrations that keep the wedges from being thrown out bythe centrifugal force SELIIIG wa and together form .a continual bearing surface all along the contactual, surfaces between the wedges and the partitions, thus. forming a strong fasteningfor the parti-' tions against bending. The partitions thus evidently will be mounted and braced in the y as a plate or disk fastened at all longitudmal points on both sides by, solid braces and will have accordingly the greatest possible resistance.

As the windings (not shown) of the'magnet do not extend into the cylindrical'projections b, the series of screw-tapped holes in such projections may be set close together in a circle, without interruption by such windings, and a correspondingly great number of fastening screws (5 may be used, making the attachment to the end plates of the shaft sections very secure. In many instances, at least, these screw-tapped, holes will be partly in said wedges 0 and partly in said partitions a, so that each screw entering a hole thus arranged will engage a wedge on one side and a relatlvely fixed partition between the winding-grooves on the other side; consequently the screws will fasten the wedges, besides attaching the magnet to the end-plates.

Having thus fully described and ascertained the nature of my said invention, what I claim and desire to secure by Letters Patent is 1. In combination with a pair of shaftsections having end-plates, a rotator body located between said end plates having longitudinal grooves for windings, longitudinal wedges fitting into said grooves for holding said windings in place, transverse terminal wedges fitting into said grooves at the ends of said body, terminal extensions formed of parts of said terminal wedges and parts of said body, and fastenlng screws entering screw-threaded holes in said extension to hold rotator body to said end plates, said screws also engaging said terminal wedges to hold them in place.

2. A rotator body provided with winding grooves, partitions between said grooves, wedges fitting in said grooves at the ends of said body and terminal extensions of reduced diameter, composed partly of portions of said partitions and partly of portions of the wedges at the ends of said body, in combination with shaft-sections having end plates and fastening screws passing through said end plates into said extensions, the screw-threaded holes of the latter for receiving said bolts being arranged in a close circle not interrupted by the windings.

3. In combination with a pair of shaft sections having end-plates, a rotator body located between said end plates, having longitudinal grooves for the windings, longitudinal wedges fitting into said grooves for holding said windings'inplace, transverse terminal wedges fitting into said groovesiat the ends-of said body, terminal extei'isions of reduced diameter formed of parts of said terminal wedges and parts of said body and fastening screws entering screw-threaded holes in said extension to .hold said rotator body to said end'plates,

said screws also engaging said terminal wedges to hold them in lace.

In testimony wliereo I have aflixed my signature in presence of two witnesses.

FREDRIK LJUNGSTROM. Witnesses:

A. W. C. BAGGE, FRANK LYON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 03 

